Our Galaxy Could Include Numerous Earth-Like Planets That Harbor Life

Clara Moskowitz writing in the WIRED SCIENCE BLOG explains that:"Earth-like planets may in fact be common in the galaxy, increasing the likelihood of extraterrestrial life." The key to making such a claim has come from the observation of "the remains of smashed up asteroids around dead stars" that revealed that the "chemical composition" of the residue "resembles the materials inside Earth and the other small, rocky inner planets of our solar system." This optimistic news was revealed at the American Astronomical Society by Michael Jura, an astronomer from UCLA who stated: "We found evidence that this asteroid dust is similar to rocks on Earth,.. This strengthens suspicions that Earth-like planets are common." Jura went on to say: "Asteroids are leftover building blocks that didn’t get incorporated into the planets,.. What we have now is a tool to measure the bulk composition of planets." Moskowitz further detailed the significance of the underlying connection between: "Asteroids and planets (which) are made from the same stuff: the dusty material that circles around young stars in disks. Eventually some of the dust clumps together and grows into planets, while asteroids represent the detritus left over. Because asteroids are formed from the same material as planets, observing asteroids around other stars can tell us crucial information about what ingredients are available to form planets around those stars." The NASA Spitzer Space Telescope was utilized by Jura and a team of experts: "to observe six dead white-dwarf stars that were coated with the debris of shredded asteroids that had collided into them. By viewing the stars through a spectrograph, which separates out light from different wavelengths, the scientists were able to observe the telltale signatures of certain chemicals in the light. Since that starlight is passing through the film of the asteroid debris, the light picked up signatures of the asteroids’ composition, too. The team found that the asteroid dust contains a glassy silicate mineral similar to minerals commonly found on Earth. They also detected a lack of carbon in the dust, which again echoes the solar system’s rocky planets and asteroids, which also have no carbon." Astronomers have made the discovery of Earth-like planets a priority because they believe that is where there may exist "the likeliest place for extraterrestrial life." In Jura's opinion, the search for "asteroid debris around dead stars" provides the most promising possibility for understanding planet formation and he and his fellow observers will continue their search for stars surrounded by asteroid dust and debris.